White‐Light Photoassisted Covalent Functionalization of Graphene Using 2‐Propanol

Abstract

of molecular species causes more subtle changes. [6,7] The edges of a graphene sheet are more reactive than the basal plane positions; hence, most covalent functionalizations are edge-selective. [8] In order to covalently functionalize the basal plane, more vigorous reaction conditions are generally required. Many of the presently used methods are via oxidation of graphite into graphene oxide using metal oxides and strong oxidizing acids. [9,10] Post-oxidation secondary functionalization of the introduced oxygen-containing functional groups [4,11] or reduction results in different types of modified graphene. The routes via graphene oxide result in defect-rich materials, where the type and extent of defects strongly depend on the initial oxidation method employed. [12,13] Alternative routes to covalently functionalized graphene employ various plasmas, atomic fluorine, or other radicals. [14][15][16][17][18][19][20][21][22] As is the case for the oxidation strategy, efficient modification of the graphene is achieved, but the harsh conditions limit the scope of functional groups that can be introduced. Thus, there is an obvious need for efficient yet mild methods for modification of the basal plane of graphene.Recently, Papadakis et al. reported that graphene can be efficiently photo(hydro)silylated and photohydrogenated at ambient temperature using white-light irradiation, [23] with the transfer photohydrogenation of graphene with formic acid as hydrogen donor being of particular interest from a process perspective. Subsequently, Koutoulogenis et al. also reported on the hydrogen atom abstraction from aldehyde substrates by graphite achieved through irradiation of graphite flakes with visible light. [24] In the present study, we have explored aliphatic alcohols as reaction partners to chemical vapor deposition (CVD)-grown graphene on Si/SiO 2 , kish graphite as well as highly oriented pyrolytic graphite (HOPG) under white-light irradiation, and we report on a novel mode of covalent graphene functionalization by 2-propanol (isopropyl alcohol (IPA)) that results in significantly more polar material than what is obtained from photo(hydro)silylation or photohydrogenation.Similar to formic acid, IPA is a known transfer hydrogenation reagent in metal-catalyzed reactions, [25] but reactions employing IPA resulted in a substantial increase of the polarity of "on chip" graphene after white-light irradiation. This is very different from what was obtained using formic acid [23] and a strong indication that IPA, in contrast to formic acid, is not Herein, a photochemical method for functionalization of graphene using 2-propanol is reported. The functionalization method which is catalyst-free operates at ambient temperature in neat 2-propanol under an inert atmosphere of argon. The equipment requirement is a white-light source for the irradiation. The same methodology when applied to kish graphite results in a novel material, exhibiting significantly higher wettability than the starting material according to water contact angle ...

Fabrication of BP2T functionalized graphene via non-covalent π–π stacking interactions for enhanced ammonia detection

“…Nevertheless, when the immersing time is longer than 2 h, the intensity ratio of I 2D /I G tends to be 1, implying the tendency of the structure evolution towards forming a bilayer graphene. [26][27][28][29] As for the D peak, it can be seen that all of the samples aer non-covalent functionalization maintains a low intensity D peak, indicating a low defect level of the graphene, which is quite different comparing to covalent graphene functionalizations. 5,30,31 In order to investigate the formation of BP2T molecule layer on graphene surface through non-covalent p-p interactions, Xray photoelectron spectroscopy (XPS) measurements were performed as shown in Fig.…”

Surface Oxidation of Ethylenechlorotrifluoroethylene (ECTFE) Membrane for the Treatment of Real Produced Water by Membrane Distillation

“…The peak at 292 eV corresponds to –CF 2 -moieties, while C 1s peak was observed at 284 eV [ 34 , 35 ]. F 1s peak was observed at 686 eV, whereas O 1s peak was noticed at 529 eV [ 36 ]. The base ECTFE membrane did not show any O peak, while on modification the O peak intensity was found to enhance at the cost of reduction in relative composition of C and F peak.…”

Superior adhesion of graphene nanoscrolls

“…Adhesion measurements. Atomic force microscope based adhesion measurements are employed to investigate the adhesion properties of the GNS [27][28][29][30][31][32] . This method is based on the nanoindentation of a sharp AFM tip made of silicon into a surface, in which the force-displacement curves shown in Fig.…”